1. Field of the Invention
The present invention relates to a system for drawing an outer cylinder of a rubber bush comprising an inner cylinder serving as a shaft member, the outer cylinder disposed around the inner cylinder and a rubber elastic body interposed between the inner cylinder and the outer cylinder.
2. Description of the Related Art
An outer appearance of the rubber bush is shown in FIGS. 1. This rubber bush 1 is used for a connecting portion of an automobile such as a suspension, and comprises a metal inner cylinder 2 serving as a shaft member, a metal outer cylinder 3 coaxially disposed around the inner cylinder 2, and an elastic body such as a rubber 4 interposed in the space between the inner cylinder 2 and the outer cylinder 3.
A molding process of the rubber bush 1 will be explained briefly. First, the inner cylinder 2 and the outer cylinder 3 are positioned in predetermined positions in a forming die. Then, rubber material is charged into the forming die an injection molding method or the like. With this process, the rubber bush 1 having a shape shown in FIG. 1 can be formed. After the rubber bush 1 is taken out from the forming die, the rubber 4 shrinks and thus, an outer peripheral portion of the rubber 4 and an inner peripheral surface 3a try to separate from each other. To prevent the separation of the rubber 4 and the outer cylinder 3, adhesive is applied to the inner peripheral surface 3a of the outer cylinder 3, thereby preventing the rubber 4 and the outer cylinder 3 from separating from each other.
However, the rubber 4 still tries to shrink after the formation, residual distortion remains in the rubber bush 1, and this residual distortion adversely affects quality of the rubber bush 1. Thereupon, in order to eliminate the residual distortion, the outer cylinder 3 is subjected to drawing working to reduce its diameter. For this purpose, a system for drawing the outer cylinder of the rubber bush 1 is known. A structure of conventional the system is shown in FIGS. 9.
FIG. 9A is a plan view of the system. This system comprises a turning table 100 on which a large number of formed rubber bush 1 are on standby, a drawing apparatus 101 for drawing an outer cylinder of the rubber bush 1, and a robot apparatus 102 for transferring the rubber bush 1 from the turning table 100 to the drawing apparatus 101.
The turning table 100 is provided with six piling portions 100A, 100B, . . . along the circumferential direction of the turning table 100. As shown in FIG. 9B, a plurality of rubber bushes 1 are piled up in the vertical direction on the piling portion. A chuck member 102a of the robot apparatus 102 grasps the rubber bush 1 located at a height of a robot grasping position of the piling portion 100A and transfers it to the drawing apparatus 101. The rubber bush 1 located at the grasping position is shown with a symbol 1A.
If the rubber bush 1 at the grasping position was transferred, the chuck member 102a sets a next rubber bush (located immediately below the transferred rubber bush) to a grasping position, a pushing-up member 103 is driven upward by means of a linear motor or the like. With this operation, the next chuck operation is ready.
At present, three rubber bushes 1 are piled up on the piling portion 100A, and if all of the rubber bushes 1 are transferred by the robot apparatus 102, the rubber bushes 1 on the other piling portion 100B are transferred.
The action in such a case will be explained. First, the pushing-up member 103 is driven downward for standby (shown with phantom line).
Next, the turning table 100 is turned in a direction of an arrow (clockwise direction) to move the piling portion 100B to a position where the piling portion 100A existed. A turning amount of the turning table 100 is about 60xc2x0 in the example shown in FIG. 9A. Then, the pushing-up member 103 is driven upward again, and one of the uppermost rubber bush 1 is grasped and set to the grasping position. Thereafter, the robot apparatus 102 restarts the transfer operation.
However, the above structure has the following problem. That is, when the piling portions are switched, an operation for retreating the pushing-up member 103 and an operation for turning the turning table 100 through a predetermined angle are required. Therefore, cycle time for transferring the rubber bush becomes longer when the piling portions are switched, which lowers productivity. More specifically, the cycle time when the piling portions are not switched can be some seconds, but if the piling portions are switched, the Cycle time is deferred to about 20 seconds.
Thereupon, it is an object of the present invention to provide a system for drawing an outer cylinder of a rubber bush having high operational efficiency and capable of maintaining the same cycle time even if piling portions are switched or not switched.
To achieve the above object, there is provided a system for drawing an outer cylinder of a rubber bush comprising an inner cylinder serving as a shaft member, the outer cylinder disposed around the inner cylinder and a rubber elastic body interposed between the inner cylinder and the outer cylinder, comprising
a first turning table having at least two piling portions on which the rubber bushes to be drawn are piled up in a vertical direction;
a second turning table having at least two piling portions on which the rubber bushes to be drawn are piled up in a vertical direction;
a first driving apparatus for bringing up the rubber bushes piled up on the piling portion of the first turning table to a predetermined robot grasping position;
a second driving apparatus for bringing up the rubber bushes piled up on the piling portion the second turning table to a predetermined robot grasping position;
a drawing apparatus having a die for drawing the outer cylinder of the rubber bush;
a robot apparatus for grasping and transferring the rubber bush located at the robot grasping position to set the same to a predetermined position of the die;
a control apparatus for controlling the robot apparatus such that the rubber bushes from the piling portion of one of the first and second turning tables are sequentially transferred to the die, and if the transfer of all the former rubber bushes from the piling portion was completed, the rubber bushes from the piling portion of the other one of the first and second turning tables and transferred.
The system of the present invention includes the first and second turning tables each having at least two piling portions on which the rubber bushes to be drawn are piled up in a vertical direction. The robot apparatus grasps and transfers the rubber bush located at the robot grasping position to the die of the drawing apparatus.
Here, it is supposed the robot apparatus sequentially transfers the rubber bushes from the piling portion of the first turning table. If all the rubber bushes piled up on the piling portion are transferred, it is necessary to switch the piling portions. At that time, the piling portion of the second turning table is selected as the piling portion on which the next rubber bush is to be transferred. While the rubber bushes are transferred from the first turning table, the second turning table can finish setting the rubber bushes to the robot grasping position. Therefore, during the switching of the piling portions, there is no loss of time by the rotating operation of the turning table and the operation of the driving apparatus. While the rubber bushes are transferred from the second turning table, the first turning table can finish setting rubber bushes to the robot grasping position. Thereafter, the transfer from the first turning table and the transfer from the second turning table are alternately repeated.
As described above, it is possible to provide a system for drawing the outer cylinder of the rubber bush capable of maintaining the same cycle time even if piling portions are switched or not switched.
As a first embodiment of the invention, it is preferable that the piling portions are provided in plural along a circumferential direction of the turning table.
By arranging the piling portions along the circumferential direction, it is possible to set the rubber bush of a predetermined piling portion to the robot grasping position by rotating the turning table.
As a second embodiment of the invention, it is preferable that each of the first and second driving apparatus includes a linear motor, and after the uppermost rubber bush of the piling portion located on the robot grasping position was transferred by the robot apparatus, the next rubber bush is brought up so as to position the next rubber bush to the robot grasping position.
With this structure, if the linear motor is driven to rise the position to the height of the rubber bush, a rubber bush to be transferred next can be stayed on standby at the robot grasping position swiftly. With this feature, a desired cycle time can be realized.
As a third embodiment of the invention, it is preferable that the drawing apparatus includes a clamping mechanism for clamping the die to a die support base, thereby making it possible to detach the die from the die support base.
There are various shapes of rubber bush depending upon vehicle types. If the shape of the rubber bush is different, the die for drawing the bush must be changed accordingly. According to the above structure, since the die is only clamped to the die support base, it is possible to replace the die in a short time.
As a fourth embodiment of the invention, it is preferable that the system further comprises
an inspection apparatus for inspecting a size of the outer cylinder of the rubber bush which was worked by the drawing apparatus;
a first passage for sending out the rubber bush which was judged as being a good product as a result of the inspection;
a second passage for sending out the rubber bush which as judged as being a bad produce as the result of the inspection; and
a switching mechanism for switching the first and second passages to which the rubber bush is sent out in accordance with the inspection result of the inspection apparatus.
After the outer cylinder of the rubber bush is drawn by the drawing apparatus, it is necessary to inspect whether the outer cylinder was drawn into a predetermined size. For this purpose, the inspection apparatus is provided. As a result of the inspection of the inspection apparatus, a good rubber bush is sent out to the first passage, and a bad rubber bush is sent out to the second passage. The switching mechanism is provided for sending out the inspected rubber bush to one of the passages. The operation of the switching mechanism is controlled based on the result of the inspection apparatus. With this feature, it is possible to reliably distinguish between good products and bad products.
As a fifth embodiment of the invention, it is preferable that the inspection apparatus comprises a snap gage, and judging means for judging that the rubber bush which could be snapped by the snap gage is the good product and the rubber bush which could not be snapped is the bad product.
If the outer cylinder of the rubber bush is drawn, the outer diameter of the outer cylinder may become greater than specs (managed value) due to wear of the die in some cases. If the outer cylinder is within the specs, the outer cylinder of the rubber bush can be snapped by the snap gage. If the outer diameter of the outer cylinder is greater than the specs, it can not be snapped by the snap gage. Therefore, it is possible to judge that a rubber bush that can not be snapped by the snap gage is a bad product.
As a sixth embodiment of the invention, it is preferable that the snap gage can move from a first position to a second position when the rubber bush is a good product, and can not move from the first position to the second position when the rubber bush is a bad product, the system is provided with a sensor for detecting a movement from the first position to the second position, and the switching mechanism is controlled based on a result of an output from the sensor.
If a rubber bush is good, since the outer cylinder thereof can be snapped by the snap gage, the snap gage can move from the first position to the second position. If the rubber bush is bad, the outer cylinder thereof can not be snapped by the snap gage, the snap gage can not move to the second position. Thereupon, the sensor for detecting the movement of the snap gage is provided, an output signal of the sensor is monitored, and it is possible to judge whether the rubber bush is good.
As a seventh embodiment of the invention, it is preferable that the system further comprises a gage support body for supporting the snap gage, the snap gage is attachable and detachable to and from the gage support body.
As described above, there are various shapes of rubber bush depending upon vehicle types. Therefore,it is necessary to prepare various snap gages so as to meet the shape of the rubber bush. By forming the snap gage such that the snap gage can be attached to and detached from the gage support body, it is easy to accept the change of the rubber bush to be drawn.
As an eighth embodiment of the invention, it is preferable that the robot apparatus comprises a chuck member for grasping the rubber bush located at the robot grasping position, and a chuck member support body for detachably supporting the chuck member.
It is also necessary that the chuck member for grasping the rubber bush can meet the different shape of the rubber bush. If various chuck members are prepared and the chuck member is formed such that the chuck member can be attached to and detached from the chuck member support body, it is easy to accept the change of the rubber bush to be drawn.
As a ninth embodiment of the invention, it is preferable that the robot apparatus comprises a chuck member for grasping the rubber bush located at the robot grasping position, and a chuck member driving mechanism capable of changing a chuck margin of the chuck member.
Instead of detachably forming the chuck member, the chuck margin of the chuck member may be changed. The chuck member may be driven by the chuck member driving mechanism to change the chuck margin. With this feature, it is easy to accept the change of the rubber bush to be drawn.
Other features and advantages of the present invention will become apparent in the following description and the accompanying drawings.